How to set Gmail to default?

I for the life of me can't figure out how to set Gmail to default.. If I choose a contact and select email it gives me the option of the stock email app, or Gmail. I just want it to take me to Gmail.. Any advice. I went into apps and settings but nothing. Thanks.. My HTC One had no issues with this.

I take it that it isn't giving the option to make Gmail the default when you choose it. If having trouble with a phone not using the program I want as default I often use this program to adjust the default settings:

I take it that it isn't giving the option to make Gmail the default when you choose it. If having trouble with a phone not using the program I want as default I often use this program to adjust the default settings: